The present invention relates to a surgical clip and, more particularly, to a clip for clamping a blood vessel to blockade, for example, a cerebral aneurysm in a surgical operation.
A cerebral aneurysm clip is a surgical instrument for clamping the base part of a cerebral aneurysm to isolate the latter from the cerebral artery. A typical cerebral aneurysm clip comprises a coiled intermediate portion and a pair of arms integrally extending therefrom in substantially the same direction to form opposite clamping jaws for clamping a blood vessel, as disclosed in U.S. Pat. No. 4,360,023 to Sugita et al.
A cerebral aneurysm can be formed at a variety of positions in intercerebral blood vessels, and an access to a position where the aneurysm exists must be made through an extremely narrow space. In order to enable such an access to the aneurysm, a combination of a clip and forceps was proposed in Japanese Patent Publication No. Hei 4-68943.
The clip proposed in this Japanese patent publication has a pair of opposing clamping arms for clamping a blood vessel. These clamping arms are arranged in a common plane. A pair of opposing engagement portions extend from the proximal ends of the clamping arms away from the arms, respectively. These engagement portions also lie in the same plane as the clamping arms. The engagement portions are of inwardly concave arcuate shape whereby the engagement portions form a substantially circular ring when the clip is closed. The two engagement portions are integrally connected by a resilient portion for urging the clamping arms in mutual abutting contact for clamping a blood vessel. The resilient portion is made up of a pair of resilient rounded wire sections each forming a convolution extending from each engagement portion at an angle to the plane mentioned above, and a resilient intermediate wire section integrally connecting the two rounded wire sections. The intermediate wire section is offset from the plane of the engagement portions.
When the clip is to be applied to a blood vessel, forceps is used to open and close the clamping arms. The forceps has on the tip ends thereof a pair of semicylindrical engaging protrusions which form a cylindrical shape combinedly when the tip ends of the forceps are closed. In a closed state of the tip ends, the cylindrically combined engaging protrusions are inserted into a space formed between the engagement portions of the clip. When the forceps is manipulated to cause the semi-cylindrical engaging protrusions to move apart, the engaging protrusions are engaged with the internal surfaces of the arcuate engagement portions to cause the engagement portions to move apart against the resiliency of the resilient portion of the clip whereby the clamping arms are opened and can be put on the blood vessel. Thereupon the clamping arms are closed to clamp the blood vessel by manipulating the forceps reversely.
This known clip is characterized in that its engagement portions can be engaged from the inside by the engaging protrusions of the forceps, to open and close the clamping arms. In the case of the clip of the U.S. patent referred to before, the engagement portions of the clip can be engaged only from the outside by relatively bulky engaging members of the forceps, so that the operator is prevented by the engaging members from viewing the clamping arms and the blood vessel to which is clamping arms are to be applied. However, in the case of the clip disclosed in the Japanese patent publication, the engaging members or protrusions of the forceps engage the engagement portions of the clip from the inside so that the engaging protrusions are small in size, thus allowing the operator to view the clamping arms and the blood vessel without being obstructed by the engaging protrusions.
The known clip described above, however, has a drawback in that when the clip is being moved to be applied to a blood vessel the clamping arms tend to move too far to such an extent that the blood vessel passes beyond the area of the clamping arms and enters the space between the engagement portions. Should this occur, the clip will not be able to clamp the blood vessel correctly between its clamping arms. This must be avoided.
Furthermore, in this known clip, there is a possibility that a blood vessel other than a blood vessel to be clamped by the clamping arms is caught in the angular area between the rounded wire sections and the intermediate joining wire sections mentioned before while the clip is being advanced toward the blood vessel to be clamped.